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Sensitivity Improvements for Picosecond Ultrasonic Thickness Measurements in Gold and Tungsten Nanoscale Films

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Nanomanufacturing and Metrology 2024年第2期7卷 1-12页

作者： Jiaqi Dong Chengyuan Yao Yuanhao Zhu Shaojie Li Bowen Liu JinTao Fan Chunguang Hu Youjian Song Minglie Hu Key Laboratory of opto-Electronic Information Science and Technology of Ministry of Education School of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China State Key Laboratory of precision Measuring Technology and instruments Tianjin UniversityTianjin 300072China

Picosecond ultrasonics,as a nondestructive and noncontact method,can be employed for nanoscale metallic film thickness *** sensitivity of the system,which determines the measurement precision and practicability of this technique,is often limited by the weak intensity of the ultrasonic *** solve this problem,we investigate the distinct mechanisms involved in picosecond ultrasonic thickness measurement for two types of metals,namely tungsten(W)and gold(Au).For thickness measurement in W films,theory and simulation show that optimizing the pump and probe laser wavelengths,which determine the intensity and shape of the ultrasonic signal,is critical to improving measurement sensitivity,while for Au film measurements,where acoustic-induced beam distortion is dominant,the signal intensity can be optimized by selecting an appropriate aperture size and sample *** above approaches are validated in experiments.A dual-wavelength pump-probe system is constructed based on a passively mode-locked ytterbium-doped fiber *** smoothing method and multipeak Gaussian fitting are employed for the extraction of ultrasonic *** measurement precision is achieved in a series of W and Au films with thicknesses of 43-750 *** work can be applied to various high-precision,noncontact measurements of metal film thickness in the semiconductor industry.

关键词： Picosecond ultrasonics Thickness measurement Optical pump-probe Beam distortion technique

Polarization-entangled photon pairs with factorable spectra engineered by using an uneven four-stage nonlinear interferometer

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Chinese Optics Letters 2024年第5期22卷 106-110页

作者：崔亮陈浩然李嘉敏李小英 college of precision Instrument and opto-electronics engineering Key Laboratory of Opto-Electronics Information TechnologyMinistry of EducationTianjin UniversityTianjin 300072China School of Physics Taiyuan University of TechnologyTaiyuan 030000China

We report the generation of polarization-entangled photon pairs in the 1550 nm band by pumping an uneven nonlinear interferometer loop with two orthogonally polarized counterpropagating pump *** uneven nonlinear interferometer,providing a more ideal interference pattern due to the elimination of secondary maxima,consists of four pieces of dispersion-shifted fibers sandwiched with three pieces of standard single-mode fibers,and the lengths of the nonlinear fibers follow the binomial *** mode number of the photon pairs deduced from the measured joint spectrum is∼*** collection efficiency of the photon pairs is found to be∼94%(after background noise correction).The directly measured visibility of two-photon interference of the polarization-entangled photon pairs is∼92%,while no interference is observed in the direct detection of either the signal or idler photons.

关键词： polarization-entangled photon pairs nonlinear interferometer quantum state engineering optical fiber

Particle distributions in Lamb wave based acoustofluidics

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Nanotechnology and precision engineering 2024年第2期7卷 60-68页

作者： Chuanchao Zhang Xian Chen Wei Wei Xuejiao Chen Quanning Li Xuexin Duan Key Laboratory of precision Measuring Technology and instruments College of Precision Instrument and Optoelectronics EngineeringTianjin UniversityTianjin300072China

Acoustic streaming enabled by a Lamb wave resonator(LWR)is efficient for particle trapping and enrichment in microfluidic ***,because Lamb waves combine the features of bulk acoustic waves and surface acoustic waves,the resulting acoustic streaming in the LWR occurs in multiple planes,and the particle flow behavior in this acoustofluidic system is largely *** here are numerical simulations and laboratory experiments conducted to investigate the boundary conditions for particle motion inside a microvortex induced by an *** dynamic capture,the particles’trajectories become orbital paths within an acoustic *** suspended particles encounter two distinct acoustic phenomena,i.e.,the drag force resulting from acoustic streaming and the acoustic radiation force,which exert forces in various directions on the *** the acoustic radiation force and the fluid drag force are dominant for large and small particles in a mixed solution,respectively,the large particles reside within the vortex while the small particles remain at its ***,when the acoustic radiation force is dominant for both types of particles,the distribution pattern is reversed.

关键词： Acoustofluidics Lamb wave resonator Particle manipulation Microvortex

Spatial light modulation for femtosecond laser manufacturing:Current developments and challenges

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Science China(Technological Sciences) 2024年第1期67卷 60-72页

作者： ZANG Xue LIU ZiTing XU YiShi WANG Yi WANG Qing LI ZhenZe WANG Lei State Key Laboratory of Integrated optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China State Key Laboratory of precision Measurement and instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China

Since the invention of lasers,spatial-light-modulated laser processing has become a powerful tool for various *** enables multidimensional and dynamic modulation of the laser beam,which significantly improves the processing efficiency,accuracy,and flexibility,and presents wider prospects over traditional mechanical technologies for machining three-dimensional,hard,brittle,or transparent *** this review,we introduce:(1)The role of spatial light modulation technology in the development of femtosecond laser manufacturing;(2)the structured light generated by spatial light modulation and its generation methods;and(3)representative applications of spatial-light-modulated femtosecond laser manufacturing,including aberration correction,parallel processing,focal field engineering,and polarization ***,we summarize the present challenges in the field and possible future research.

关键词： femtosecond laser manufacturing spatial light modulation structured light aberration correction parallel processing focal field engineering polarization control

Coherent terahertz wave emission from laser-induced plasma in isotropic transparent solid dielectrics

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Chinese Optics Letters 2024年第7期 126-130页

作者：陈宇轩何宇航戴辰殷喇向宇田震戴建明 Center for Terahertz Waves and School of precision Instrument and opto-electronics engineering Tianjin University

In this Letter, we employ fused silica and two types of optical glass as examples to investigate the coherent terahertz(THz)wave emission from laser-ionized isotropic transparent dielectrics. Based on the laser energy and incident angle dependences, we ascribe the THz emission to the ponderomotive force-induced dipole oscillation. Additionally, our investigation on the dependence of THz amplitude on the laser pulse duration confirms the dominant role of avalanche ionization in solid dielectrics. The THz emission can be utilized to indirectly monitor the ultrafast dynamics of carrier generation and motion during the laser ionization process of solid dielectrics.

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Full-Stokes metasurface polarimetry requiring only a single measurement

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Photonics Research 2024年第3期12卷 514-521页

作者： CHENGLONG ZHENG HUI LI JINGYU LIU MENGGUANG WANG HUAPING ZANG YAN ZHANG JIANQUAN YAO Key Laboratory of Material Physics Ministry of EducationSchool of Physics and MicroelectronicsZhengzhou UniversityZhengzhou 450052China Key Laboratory of opto-electronics Information Technology(Tianjin University) Ministry of EducationSchool of Precision Instruments and Opto-Electronics EngineeringTianjin UniversityTianjin 300072China Beijing Key Laboratory for Metamaterials and Devices Key Laboratory of Terahertz OptoelectronicsMinistry of Educationand Beijing Advanced Innovation Center for Imaging TechnologyDepartment of PhysicsCapital Normal UniversityBeijing 100048China State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringZhejiang UniversityHangzhou 310027China

Polarization is crucial in various fields such as imaging,sensing,and substance detection.A compact,fast,and accurate polarization detection device is vital for these ***,we demonstrate a multifocus metalens for terahertz polarization detection that requires only a single measurement to obtain complete polarization parameters and reconstruct the polarization state of the incident *** individual subarrays of this metalens convert each of the six polarized components into the same polarization,which in turn links the Stokes parameters to these six *** incident linear polarizations and elliptical polarizations are characterized by Stokes parameters and polarization *** and experimental results show that the scheme can accurately detect the incident polarization with a single *** proposed metasurface polarimetry may find applications in the fields of real-time terahertz detection and integrated optics.

关键词： field incident polar

Low-Voltage IGZO Field-Effect Ultraviolet Photodiode

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Chinese Physics Letters 2024年第6期41卷 156-161,I0001-I0003页

作者：宋双梁会力霍文星张广张永晖王绩伟梅增霞 Songshan Lake Materials Laboratory Dongguan 523808China Institute of Physics Chinese Academy of SciencesBeijing 100190China college of Physics Liaoning UniversityShenyang 110036China Department of instruments Science and Technology School of Precision Instrument and Opto-electronics EngineeringTianjin UniversityTianjin 300072China National Key Laboratory of Scattering and Radiation Beijing 100039China School of Physics and optoelectronic engineering Shandong University of TechnologyZibo 255000China

In the era of Internet of Things(Io Ts),an energy-efficient ultraviolet(UV)photodetector(PD)is highly desirable considering the massive usage scenarios such as environmental sterilization,fire alarm and corona discharge *** far,common self-powered UV PDs are mainly based on metal-semiconductor heterostructures or p–n heterojunctions,where the limited intrinsic built-in electric field restricts further enhancement of the *** this work,an extremely low-voltage field-effect UV PD is proposed using a gatedrain shorted amorphous IGZO(a-IGZO)thin film transistor(TFT)architecture.A combined investigation of the experimental measurements and technology computer-aided design(TCAD)simulations suggests that the reverse current(ⅠR)of field-effect diode(FED)is highly related with the threshold voltage(Vth)of the parental TFT,implying an enhancement-mode TFT is preferable to fabricate the field-effect UV PD with low dark *** by a low bias of-0.1 V,decent UV response has been realized including large UV/visible(R_(300)/R_(550))rejection ratio(1.9×10^(3)),low dark current(1.15×10^(-12)A)as well as high photo-to-dark current ratio(PDCR,~10^(3))and responsivity(1.89 A/W).This field-effect photodiode provides a new platform to construct UV PDs with well-balanced photoresponse performance at a low bias,which is attractive for designs of large-scale smart sensor networks with high energy efficiency.

关键词： IGZO attractive ultraviolet

Laser manufacturing of spatial resolution approaching quantum limit

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Light(Science & Applications) 2024年第3期13卷 421-428页

作者： Xiao-Jie Wang Hong-Hua Fang Zhen-Ze Li Dan Wang Hong-Bo Sun State Key Laboratory of precision Measurement Technology and instruments Department of Precision InstrumentTsinghua UniversityBeijing 100084China State Key Laboratory of Integrated optoelectronics College of Electronic Science and EngineeringJilin University2699 Qianjin StreetChangchun 130012China

Atomic and close-to-atom scale manufacturing is a promising avenue toward single-photon emitters,single-electron transistors,single-atom memory,and quantum-bit devices for future communication,computation,and sensing *** manufacturing is outstanding to this end for ease of beam manipulation,batch production,and no requirement for *** is,however,suffering from optical diffraction ***,we report a spatial resolution improved to the quantum limit by exploiting a threshold tracing and lock-in method,whereby the two-order gap between atomic point defect complexes and optical diffraction limit is surpassed,and a feature size of<5 nm is *** underlying physics is that the uncertainty of local atom thermal motion dominates electron excitation,rather than the power density slope of the incident *** show that the colour centre yield in hexagonal boron nitride is transformed from stochastic to deterministic,and the emission from individual sites becomes polychromatic to *** a result,single colour centres in the regular array are deterministically created with a unity yield and high positional accuracy,serving as a step forward for integrated quantum technological applications.

关键词： quantum limit resolution

Sawtooth-enhanced bend sensor for gesture recognition

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Science China(Technological Sciences) 2024年第6期67卷 1727-1736页

作者： BAI YanRu ZHANG ZiHang WANG HaoYu GUO Rui LI XiSheng School of Automation and Electrical engineering University of Science and Technology BeijingBeijing100083China School of Advanced engineering University of Science and Technology BeijingBeijing100083China School of precision Instrument and opto-electronics engineering Tianjin UniversityTianjin300072China School of Computer and Communication engineering University of Science and Technology BeijingBeijing100083China

Gesture recognition has diverse application prospects in the field of human-computer ***,gesture recognition devices based on strain sensors have achieved remarkable results,among which liquid metal materials have considerable advantages due to their high tensile strength and *** improve the detection sensitivity of liquid metal strain sensors,a sawtooth-enhanced bending sensor is proposed in this *** with the results from previous studies,the bending sensor shows enhanced resistance *** addition,combined with machine learning algorithms,a gesture recognition glove based on the sawtooth-enhanced bending sensor is also fabricated in this study,and various gestures are accurately *** the fields of human-computer interaction,wearable sensing,and medical health,the sawtooth-enhanced bending sensor shows great potential and can have wide application prospects.

关键词： liquid metal bending sensor gesture recognition machine learning